1. Field of Invention
This invention is directed to systems, methods and structures for dissipating heat in fluid ejector heads.
2. Description of Related Art
A variety of systems, methods and structures are conventionally used to dissipate heat in a thermal fluid ejector head. The thermal fluid ejector heads of fluid ejection devices, such as, for example, ink jet printers, generate significant amounts of residual heat as the fluid is ejected by heating the fluid to the point of vaporization. This residual heat will change the performance, and ultimately the ejection quality, if the excess heat remains within the fluid ejector head. Changes in ejector performance are normally manifested by a change in the drop size, firing sequence, or other related ejection metrics. Such ejection metrics desirably remain within a controllable range for acceptable ejection quality. During lengthy operation or heavy coverage ejection, the temperature of the thermal fluid ejector head can exceed an allowable temperature limit. Once the temperature limit is exceeded, a slow down or cool down period is normally used to maintain the ejection quality.
Many fluid ejection devices, such as, for example, printers, copiers and the like, improve throughput by improving thermal performance. One technique to improve fluid ejector head performance is to divert excess heat into the fluid being ejected. Once the fluid being ejected has exceeded a predetermined temperature, the hot fluid is ejected from the fluid ejector head. During lengthy operation or heavy coverage ejection, this technique is also susceptible to temperatures in the fluid ejector head exceeding an allowable temperature limit.
Another technique is to use a heat sink to store heat, or conduct heat away, from the fluid ejector head. Typically, heat sinks are made from copper, aluminum or other materials having high thermal conductivity to remove heat from the thermal fluid ejector head. U.S. patent application Ser. No. 10/600,507, which is incorporated herein by reference in its entirety, discloses various exemplary embodiments of such heat sinks molded from a polymer mixed with at least one thermally-conductive filler material.
Heat sinks, however, add additional weight, size, cost and/or energy usage to the fluid ejector head. Each of these becomes disadvantageous when heat sinks are applied to fluid ejector heads that are translated past a receiving medium. Additionally, many fluids typically employed in fluid ejector heads, such as inks, use solvents and/or salts which are likely to corrode aluminum, copper and other like heat sink materials.
Other systems, methods and structures usable to conduct heat away from thermal fluid ejector heads include manufacturing and/or molding various print cartridge and fluid ejector carriage elements and components from thermally-conductive materials, to include a polymer or a polymer material mixed with at least one thermally-conductive filler material. U.S. patent application Ser. No. 10/721,221 and U.S. patent application Ser. No. 10/629,606, each incorporated herein by reference in its entirety, disclose various embodiments for thermally-conductive fluid ejector carriages and fluid ejector print cartridge components molded from polymers.